Add a "fork" of musl as //fusl.

fusl/src/linux/eventfd.c

Index: fusl/src/linux/eventfd.c
diff --git a/fusl/src/linux/eventfd.c b/fusl/src/linux/eventfd.c
new file mode 100644
index 0000000000000000000000000000000000000000..68e489c83647e71f947ba616a154d9f11f44a85e
--- /dev/null
+++ b/fusl/src/linux/eventfd.c
@@ -0,0 +1,23 @@
+#include <sys/eventfd.h>
+#include <unistd.h>
+#include <errno.h>
+#include "syscall.h"
+
+int eventfd(unsigned int count, int flags)
+{
+	int r = __syscall(SYS_eventfd2, count, flags);
+#ifdef SYS_eventfd
+	if (r==-ENOSYS && !flags) r = __syscall(SYS_eventfd, count);
+#endif
+	return __syscall_ret(r);
+}
+
+int eventfd_read(int fd, eventfd_t *value)
+{
+	return (sizeof(*value) == read(fd, value, sizeof(*value))) ? 0 : -1;
+}
+
+int eventfd_write(int fd, eventfd_t value)
+{
+	return (sizeof(value) == write(fd, &value, sizeof(value))) ? 0 : -1;
+}